This shouldn't be possible in fact. Idea is that engine only line players in training, in case that no other players are available.

Despite this being possible, don't hink you're getting an advantage on doing it in purpose, you're loosing more than you win, because there's a penalty for every empty spot on the line up and penalty is not that small.

We'll analyse this situation and decide if we change it or leave it like this. Again, tks for reporting it!